NCT00347048.

Methods	Study design: randomised, parallel‐group trial Quadruple blinding (participant, care provider, investigator, outcomes assessor) Settings: multicentre in Japan Study period: September 2006 to April 2008
Participants	Inclusion criteria: moderate‐to‐severe refractory UC; disease activity: > 4 stools a day, bloody stool, moderate‐to‐severe endoscopic finding; steroid resistance or dependence to meet ≥ 1 of the following condition: no efficacy with > 40 mg/day or 1 mg/kg/day of steroid over ≥ 1 week, no efficacy with 30–40 mg/day of steroid over ≥ 2 weeks, exacerbation along with steroid reduction; age 16–64 years. Exclusion criteria: mild/fulminant UC; hepatic or renal (or both) failure (people receiving 6‐mercaptopurine, cyclosporin or other immunosuppressants within 12 weeks prior to screening); received leukocytapheresis or granulocytapheresis within 2 weeks prior to entry; receiving steroids or started new dose of steroids < 2 weeks before enrolment; changed the dose of steroid or started steroid within 1 week prior to entry in case they received > 40 mg/day or 1 mg/kg/day of steroid just before the study. 67 participants Disease activity: NR Disease duration: NR Extent of disease: NR Age: 16–64 years Sex (M/F): NR Concurrent therapies: NR Number enrolled: NR Number randomised: NR Number reaching end of study: NR
Interventions	IG: tacrolimus CG: placebo
Outcomes	Primary outcome: improvement of DAI score Duration: 2 weeks Secondary outcomes: Changes of DAI score in total and in each component Change in clinical severity and symptoms Endoscopic findings Participant's impression Requirement of steroid Duration: 2 weeks Length of intervention and follow‐up points: 12 weeks Definition of remission or clinical improvement by study authors: NR Number of participants who achieved remission: NR Number of participants who achieved clinical improvement: NR Time to onset of action for tacrolimus from beginning of study: NR Number of participants who required other rescue medication: NR Time to other rescue medication from beginning of study: NR Number of participants who underwent surgery: NR Time to surgery from beginning of study: NR Adverse events: NR Withdrawal due to adverse events: NR Serious adverse events: NR Time to adverse events from beginning of study: NR
Notes	No email address on trials webpage or on the responsible party (Astellas Pharma Inc), only telephone number provided.

CG: control group; DAI: Disease Activity Index; F: female; IG: intervention group; M: male; NR: not reported; RCT: randomised controlled trial; UC: ulcerative colitis.